Field of the Disclosed Subject Matter
The present disclosed subject matter relates to a reactor vessel having an internal support assembly, and particularly to an assembly and method to support pressure vessel internal hardware within a multi-phase reaction bed vessel.
Description of Related Art
Fluid catalytic cracking (FCC) processes are used for petroleum and petrochemical conversion processes. These processes can provide efficient and selective catalytic cracking of hydrocarbon-containing feedstock. For example, small catalyst particles can be fluidized and mixed with a feedstock by intimate contact under thermally active conditions to generally produce lower molecular weight “cracked” products. FCC processes are beneficial due at least in part to the ability to continuously recycle and regenerate the spent catalysts and to process large volumes of hydrocarbon-containing feedstock.
In FCC processes, higher molecular weight feeds contact fluidized catalyst particles, most advantageously in the riser reactor of the fluidized catalytic cracking unit. Contact between feed and catalyst can be controlled according to the type of product desired. In catalytic cracking of the feed, reactor conditions, including temperature and catalyst circulation rate, can be adjusted to increase formation of the desired products and reduce the formation of less desirable products, such as light gases and coke.
Various fluidized catalytic cracking reactor riser and reactor vessel designs can be utilized. For example, certain fluidized catalytic cracking reactors utilize a short contact-time cracking configuration. With this configuration, the catalyst contacts the fluidized catalytic cracker feedstream for a limited time in order to reduce excessive cracking, which can result in the increased production of less valued products such as light hydrocarbon gases, as well as increased coking deposition on the cracking catalysts.
Certain fluidized catalytic cracking configurations utilize a reactor riser cracking configuration wherein the catalyst can contact the fluidized catalytic cracker feedstock in a reactor riser, and the catalyst and the hydrocarbon reaction products can be separated shortly after the catalyst and hydrocarbon mixture flows from the reactor riser into the fluidized catalytic cracking reactor. Many different fluidized catalytic cracking reactor designs are known. For example, certain designs utilize mechanical cyclones internal to the reactor to separate the catalyst from the hydrocarbon reactor products. This separation process can reduce post-riser reactions between the catalyst and the hydrocarbons as well as separate the cracked hydrocarbon products for further processing from the spent catalyst, which can be regenerated and reintroduced into the reaction process.
Catalyst separated from the cracked hydrocarbon products in the FCC reactor can be considered as “spent catalyst” until such time as the catalyst can typically be sent to an FCC regenerator vessel and regenerated into a “regenerated catalyst.” In such a process, the spent catalyst can flow through a gaseous stream stripping section to remove most or all of the hydrocarbon layer remaining on the catalyst after separation from the bulk of the FCC products. This “stripped” catalyst can then be sent via a spent catalyst riser to an FCC regenerator to oxidize the spent catalyst and burn away the remaining hydrocarbons and coke to convert the spent catalyst to regenerated catalyst.
The stripping section can include various vessel hardware supported and/or suspended within the reactor bed vessel. The vessel hardware can include multiple objects having dissimilar or irregular shapes. Certain support structures for vessel hardware typically include parallel chord members secured to the cylindrical vessel wall. Such chord members are secured to the cylindrical vessel wall in alignments other than radial, which can introduce unsuitable material stress concentration levels and undesirable refractory junctions at the connection point with the vessel wall. Furthermore, the non-radial connection formed at a bi-material junction of steel with a gunned refractory system can introduce irregular fractures through the lining, which can affect gas flow paths and lead to non-uniform elevated shell temperatures or “hot spots” that can affect performance of the vessel and lead to costly repairs. Additionally, the non-radial chord members can introduce space limitations within the vessel wall that can hinder or prevent workman access for inspection and repair, and require specialized rigging equipment to install.
As such, there remains a need for assemblies and methods to support vessel hardware in a reaction bed vessel, as well as provide improved connections to the reaction bed vessel.